Air-conditioning apparatuses, such as a multi-air-conditioning apparatus for a building, include an air-conditioning apparatus in which a refrigerant is circulated between an outdoor unit and a relay unit and a heat medium, such as water, is circulated between the relay unit and an indoor unit to reduce conveyance power for the heat medium while circulating the heat medium, such as water, through the indoor unit (refer to Patent Literature 1, for example).
In some related-art refrigeration cycle apparatuses, such as a multi-air-conditioning apparatus for a building, for example, a refrigerant pipe and a pipe part of a device are heated using, for example, a burner and are fixed (connected) with a brazing material (or by brazing). In a case where a part constituting a refrigerant circuit is broken and therefore has to be replaced in such a refrigeration cycle apparatus, the use of a nonflammable refrigerant permits, for example, a refrigerant pipe to be heated with a burner or the like immediately after recovery of the refrigerant in a recovery tank, such that the brazing material can be melted and the refrigerant pipe can be removed and replaced.
In an air-conditioning apparatus recently developed, an operation procedure which avoids ignition during part replacement in the use of a flammable refrigerant is defined (refer to Patent Literature 2, for example).